In a signal transmission process, parameters such as a waveform, a subcarrier spacing, and a symbol period need to be selected. Currently, the parameters such as the subcarrier spacing, symbol period, and waveform are selected according to a ratio of multipath delay spread and Doppler spread of a channel.
Specifically, during selection, first, τmax, τms, and fd of a channel are obtained through estimation. During selection of a waveform parameter, if a waveform satisfies
                                          W            t                                W            f                          =                                            τ              max                                      f              d                                ⁢                                          ⁢          or                                    (                  formula          ⁢                                          ⁢          1                )                                                                    W              t                                      W              f                                =                      1.5            ⁢                                          τ                rms                                            f                d                                                    ,                            (                  formula          ⁢                                          ⁢          2                )            the waveform is selected. During selection of a symbol period and a subcarrier spacing, if a symbol period and a subcarrier spacing satisfy
                              T          F                =                                            τ              max                                      f              d                                ⁢                                          ⁢          or                                    (                  formula          ⁢                                          ⁢          3                )                                                      T            F                    =                      1.5            ⁢                                          τ                rms                                            f                d                                                    ,                            (                  formula          ⁢                                          ⁢          4                )            the symbol period and the subcarrier spacing are selected, where W1 is waveform time spread, Wf is waveform frequency spread, T is the symbol period, F is the subcarrier spacing, τmax is maximum channel multipath delay spread, fd is maximum channel Doppler spread, and τms is root mean square delay spread of the channel.
A premise to ensure that the selected subcarrier spacing and symbol period are preferable configuration parameters is that a channel scattering function is a constant. However, this premise is difficult to satisfy in practice. If a channel does not satisfy the premise, but a transmit end still transmits a signal by using the selected waveform, subcarrier spacing, and symbol period, accuracy of a signal obtained through demodulation by a receive end receiving the signal is relatively low. In addition, the channel parameters τmax, τms, and fd that need to be obtained sometimes need to be fed back to the transmit end after being measured by the receive end (for example, user equipment feeds back the parameters to a base station after measurement). However, these parameters are continuous values, and feedback overheads after quantization are relatively high. Therefore, the foregoing method further has a disadvantage of relatively high overheads. Orthogonal frequency division multiplexing (OFDM) uses a rectangular waveform, and frequency spread Wf of the rectangular waveform is infinite. Therefore, the foregoing method is not applicable to configurations of the subcarrier spacing and the symbol period in an OFDM system. Therefore, the current signal transmission method has disadvantages of relatively low accuracy of a signal obtained through demodulation by the receive end and relatively high feedback overheads.